The present invention relates to the bearing of an idler gear in an all-wheel transfer transmission of a motor vehicle. The idler gear is disposed between first and second casing walls of a transmission case and mate with both a drive gear wheel originating from the locking system and an output gear driving one vehicle axle.
In an all-wheel transfer transmission shown in German Published Unexamined Patent Application No. 3,604,143, the distance between the axes of the drive shaft originating from the all-wheel locking system and of the output shaft driving one vehicle axle must be relatively large in order to be able to laterally move this output shaft past the large-volume housing of the gear-shift transmission. If large gear wheels that mate with one another were used on the drive shaft and on the output shaft, the two vehicle axles would be driven in different rotating directions. A transfer transmission is therefore used that comprises a gear wheel of the drive shaft, an idler gear and a gear wheel on the output shaft.
It is an objective of the invention to provide a bearing for the idler gear of such an arrangement that can be manufactured cost-effectively and in a simple manner ensures a bearing adjustment that is free from play, as well as the concentric running of the idler gear.
This and other objectives are achieved in the present invention by providing a bearing for an idler gear which has a bush on which the idler gear is disposed. This bush has at least one side with a stop collar which rests against one casing wall. The other side of the bush is axially braced on the outside with respect to the other casing wall by means of a tightenable connection.
If the idler gear is disposed on a bush that, by means of a screwed connection, axially braces the two casing walls of the transmission casing with one another, when the screwed connection is tightened, the axial play of the bearing clamped in between the two casing walls is made to equal zero.
In an advantageous embodiment of the present invention, for the tightenable connection, a screwed connection is used with a screw that passes through the center of the bush and with its head, in the area of one casing wall, rests against the bush and that by means of a nut from the outside is braced with respect to the other casing side. In this embodiment, the bush that is fitted into a smooth through-bore of the transmission casing, with a stop collar, is placed against one side of the casing. The transmission casing which can be constructed of light metal and the casing walls of which are elastically bendable, is reinforced by the bush when the screwed connection is tightened and therefore causes less noise-generating sound radiation.
When the idler gear is disposed on tapered roller bearings, the tightening of the tightenable connection ensures a precise concentricity. In an advantageous embodiment, the hub of the idler gear is a joint outer race of the tapered roller bearings and directly represents the running surface of the tapered roller bearings. Via the inner races of the tapered roller bearings that are clamped in between the two casing walls and the spacer that is disposed between them and in its length is precisely tolerated, the tapered rollers, when the tightenable connection is tightened, are placed against the idler gear so that the radial play of the bearing becomes zero.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.